Composition containing anti-misting component

ABSTRACT

The invention relates to coating formulations comprising (i) a silicone-based coating component susceptible to misting under mist-producing conditions; and (ii) an anti-misting amount of a branched polysiloxane component resulting from copolymerizing under hydrosilylation conditions a component mixture comprising (a) one or more organosilicon compounds containing at least two unsaturated hydrocarbon functional groups per molecule, and (b) one or more silylhydride-containing compounds containing at least two silylhydride functional groups per molecule, with the provision that (i) at least one component (a) or (b) contains at least three functional groups per molecule; (ii) a component (a) or (b) having a higher number of functional groups per molecule is present in a molar amount equal to or lower than a molar amount of the other component (a) or (b) having a lower number of functional groups per molecule; and (iii) unsaturated hydrocarbon compounds are excluded from the component mixture. The invention also relates to a process for coating a substrate with the above coating formulation, as well as hardened silicone-based coatings or films obtained by subjecting the coated substrate to one or more curing steps.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to compositions containing mist suppressantcompositions and their particular use in coating processes where areduced level of misting or aerosoling is desired.

2. Description of the Prior Art

It is well known that in operations where silicone-based paper releasecoating formulations are subjected to a high enough rotational ortranslational motion, e.g., in high speed roll coating of flexiblesupports and paper, misting and/or aerosoling can become significantproblems. These problems become particularly significant when applyingthese release coatings at roll coating speeds approaching 1000 ft/min,while the trend in the paper coating industry is to use speeds in excessof 1500 ft/min, e.g., 2000-3000 ft/min. In addition to having adeleterious effect on manufacturing operations, these mist and aerosolparticles present industrial hygiene and safety issues for those peopleoperating or working in the vicinity of the coating equipment.

Specialized chemical formulations known generically as “mistsuppressants” have commonly been used to reduce the formation of mist insuch operations. For example, U.S. Pat. Nos. 6,805,914 and 6,489,407(hereinafter the '914 and '407 patents) disclose silicone mistsuppressant compositions derived from reacting an excess of at least oneorganohydrogensilicone compound containing at least three silicon-bondedhydrogen groups per molecule (component (a)) with at least one compoundcontaining at least two alkenyl groups per molecule (component (b)),wherein the ratio of the number of silicon-bonded hydrogen atoms ofcomponent (a) to the number of alkenyl groups of component (b) is atleast 4.6:1, and more preferably from 4.6:1 to 500:1.

U.S. Pat. No. 6,586,535 discloses essentially the inverse of the '914and '407 patents, i.e., silicone mist suppressant compositions derivedfrom reacting at least one organohydrogensilicon compound containing atleast two silicon-bonded hydrogen groups with an excess of at least oneorganoalkenylsiloxane compound containing at least three silicon-bondedalkenyl groups, wherein the ratio of the number of silicon-bondedhydrogen atoms of component (a) to the number of alkenyl groups ofcomponent (b) is less than or equal to 1:4.6, and preferably from 1:4.6to 1:500.

U.S. Pat. Nos. 6,764,717 and 6,956,096 disclose silicone-based mistsuppressant compositions derived from a two-step process involving: (a)reacting a hydrocarbon containing at least three aliphatic double bondswith a stoichiometric excess of organosiloxane compounds having terminalsilicon-bonded hydrogen atoms, wherein the ratio of silicon-bondedhydrogen to aliphatic double bonds is from 1.3 to 10, and preferablyfrom 1.5 to 5; and (b) reacting the resulting hydrocarbon-siloxanecopolymers, which contain silicon-bonded hydrogen atoms, with astoichiometric excess of α,ω-dialkenylsiloxane polymer, wherein theratio of aliphatic double bonds in the α,ω-dialkenylsiloxane polymer tosilicon-bonded hydrogen in the hydrocarbon-siloxane copolymer obtainedin the first step is from 1.2 to 10, preferably from 1.5 to 5.0.

U.S. Pat. Nos. 6,887,949, 6,774,201, and 6,727,338 disclose siliconepolymers as anti-mist additives wherein unsaturated hydrocarboncompounds are included in the synthesis of the silicone polymers.

U.S. Pat. No. 5,625,023 discloses mist suppressant compositions derivedby reacting an organosilicon compound, an oxyalkylene-containingcompound, and a catalyst.

U.S. Pat. No. 5,399,614 discloses adhesive compositions containingalkenyl-terminated polydiorganosiloxanes and silylhydride-terminatedorganohydrogenpolysiloxanes.

However, there remains a need for coating compositions, particularlypaper release compositions, having a reduced level of misting when usedin mist-producing processes, particularly in high-speed coatingprocesses, while providing other benefits, such as cost savings, ease ofproduction, and ease of use.

BRIEF DESCRIPTION OF THE INVENTION

These and other objectives have been achieved, firstly, by providing acomposition (i.e. coating formulation) comprising:

-   -   (i) a silicone-based coating component susceptible to misting        under mist-producing conditions; and    -   (ii) an anti-misting amount of a branched polysiloxane component        resulting from copolymerizing under hydrosilylation conditions a        component mixture comprising:        -   (a) one or more organosilicon compounds containing at least            two unsaturated hydrocarbon functional groups per molecule,            said unsaturated hydrocarbon functional groups capable of            undergoing a hydrosilylation reaction with a            silylhydride-containing compound under hydrosilylation            conditions; and        -   (b) one or more silylhydride-containing compounds containing            at least two silylhydride functional groups per molecule;

provided that (i) at least one component (a) or (b) contains at leastthree functional groups per molecule; (ii) when one component (a) or (b)has a higher number of functional groups per molecule than anothercomponent (a) or (b) having a lower number of functional groups permolecule, then the component (a) or (b) having a higher number offunctional groups per molecule is present in a molar amount equal to orlower than the molar amount of the component (a) or (b) having a lowernumber of functional groups per molecule; and (iii) unsaturatedhydrocarbon compounds are excluded from the component mixture.

In one embodiment, the unsaturated hydrocarbon functional groups ofcomponent (a) are in a molar ratio to silylhydride functional groups ofcomponent (b) within a range according to a formula (6−s): 1 or 1:(1+t)where s represents a number equal to or greater than 0 and less than 5,and t represents a number greater than 0 and equal to or less than 5.

In another embodiment, the unsaturated hydrocarbon functional groups ofcomponent (a) are in a molar ratio to silylhydride functional groups ofcomponent (b) within a range according to a formula (4.6−s): 1 or1:(1+s) where s represents a number greater than 0 and less than 3.6.

In another embodiment, the unsaturated hydrocarbon functional groups ofcomponent (a) are in a molar ratio to silylhydride functional groups ofcomponent (b) within a range according to a formula (4.25−s): 1 or1:(1+t) where s represents a number equal to or greater than 0 and lessthan 3.25, and t represents a number greater than 0 and equal to or lessthan 3.25.

In yet another embodiment, the unsaturated hydrocarbon functional groupsof component (a) are in a molar ratio to silylhydride functional groupsof component (b) within a range of about 4.5:1 to about 2:1.

In particular embodiments, one component (a) or (b) has at least four,or at least six, or at least eight, or a higher number of functionalgroups per molecule, and is in a lower molar amount than the othercomponent (a) or (b) having two or three functional groups per molecule.

The invention is also directed to a coating process comprising applyingto a substrate under mist-producing conditions the coating formulationsdescribed above. The coating formulation exhibits reduced misting whensubjected to these mist-producing conditions as compared to the samecomposition lacking the anti-misting amount of branched polysiloxanecomponent.

The invention is also directed to a hardened silicone-based coating orfilm produced by subjecting a substrate coated with the coatingformulations, as described above, to one or more curing steps.

The present invention advantageously provides paper release, adhesive,and related coating compositions containing novel branched polysiloxanemist suppressants. The compositions containing these mist suppressantsare capable of significant reductions in misting during high speedcoating operations while affording the additional benefits of beingeconomical and simple to use and make.

DETAILED DESCRIPTION OF THE INVENTION

The compositions of the invention contain, minimally, two components:(i) a silicone-based coating component susceptible to misting undermist-producing conditions; and (ii) an anti-misting amount of a branchedpolysiloxane component (the anti-misting component).

The silicone-based coating component must be of such a flowableconsistency that it can be applied to a substrate as a coating, e.g., byroll-coating, spraying, and the like. For example, the silicone-basedcoating component can be an uncured or partially cured liquid having aviscosity low enough so that it can be readily applied as a coating on asubstrate. Typically, the silicone-based coating component has aviscosity below 1,500 centipoise (cPs), more typically in the range 50to 1,000 cPs, and even more typically in the range 50 to 500 cPs, where1 centipoise (cPs)=1 millipascal-second (mPa·s).

The silicone-based coating component can be directed to any applicationfor which a silicone-based coating is useful, e.g., as release agents,lubricants, protectants, adhesives, and so on. A particularly suitabletype of silicone-based coating component includes the well-known classof pressure-sensitive adhesives, which have the property of adhering toa surface and being easily removed therefrom without transferring morethan trace quantities of the adhesive to the substrate surface.

For example, the silicone-based coating component can be any of thecurable silicone coating or paper release compositions known in the art.Some examples of classes of curable silicone coating compositions arethose which are curable by hydrosilylation reaction crosslinking,peroxide curing, photocuring (e.g., UV curing), and electron beamcuring.

In one embodiment, the silicone-based coating component includescomponents capable of crosslinking under hydrosilylation reactionconditions, e.g., in the presence of a hydrosilylation catalyst, asfurther discussed below. The components capable of crosslinking underhydrosilylation reaction conditions include (i) one or moreorganosilicon compounds containing at least two unsaturated hydrocarbonfunctional groups per molecule, and (ii) one or moresilylhydride-containing compounds containing at least two silylhydridefunctional groups per molecule. Some examples of unsaturated hydrocarbongroups of component (i) include vinyl, allyl, 3-butenyl, 4-pentenyl,5-hexenyl, 6-heptenyl, 7-octenyl, 8-noneyl, 9-decenyl, 10-undecenyl,4,7-octadienyl, 5,8-nonadienyl, and the like.

The unsaturated organosilicon compound of component (i) and thesilylhydride-containing compound of component (ii) can be,independently, for example, a low molecular weight silane, disilane,trisilane, siloxane, disiloxane, trisiloxane, cyclotrisiloxane, orcyclotetrasiloxane compound, or the like, having either: at least twounsaturated hydrocarbon groups for the case of component (i), or atleast two silylhydride functional groups for the case of component (ii).The examples given later on in this specification for each of thesetypes of compounds for the anti-misting component apply here as well.

Alternatively, components (i) and/or (ii) can be any of the linear,branched, and/or crosslinked polymers having any two or more of acombination of M, D, T, and Q groups, wherein, as known in the art, an Mgroup represents a monofunctional group of formula R₃SiO_(1/2), a Dgroup represents a bifunctional group of formula R₂SiO_(3/2), a T grouprepresents a trifunctional group of formula RSiO_(3/2), and a Q grouprepresents a tetrafunctional group of formula SiO_(4/2), wherein the Rgroups can be any suitable groups including hydrogen, hydrocarbon (e.g.,C₁-C₆), halogen, alkoxy, and/or amino groups, and wherein at least twoof the R groups in the siloxanes described above are either: at leasttwo unsaturated hydrocarbon groups for the case of component (i), or atleast two silylhydride functional groups for the case of component (ii).Some examples of classes of polysiloxanes suitable for thesilicone-based coating components include the MDM, TD, MT, MDT, MDTQ,MQ, MDQ, and MTQ classes of polysiloxanes, and combinations thereof,having either: at least two unsaturated hydrocarbon groups for the caseof component (i), or at least two silylhydride functional groups for thecase of component (ii).

For example, the silicone-based coating component can be a standardsilicone paper release formulation containing 90-99% by weight of avinylated polydimethylsiloxane polymer and 1-10% by weight of asilylhydride-functionalized siloxane-based compound or polymer based onthe total weight of the silicone-based coating component, wherein eachof the vinyl-containing and silylhydride-containing components typicallyhas a viscosity in the range of about 20-500 cPs.

Typically, a catalyst inhibitor is included in the coating formulationin order to prevent curing of the catalyst during processing or toextend bath life or stability to the formulation during storage. Thecatalyst inhibitor can be any chemical known in the art which caninhibit the catalyst from curing during the coating process while notpreventing curing when curing is desired. For example, the catalystinhibitor can be a chemical which will sufficiently inhibit the catalystfrom curing at room temperature during application of the coatingformulation, but loses its inhibitory effect on being subjected toelevated temperatures when cure is desired. The inhibitor is typicallyincluded in the composition in an amount of about 5 to about 15 parts byweight of the composition. Some examples of catalyst inhibitors includemaleates, fumarates, unsaturated amides, acetylenic compounds,unsaturated isocyanates, unsaturated hydrocarbon diesters,hydroperoxides, nitrites, and diaziridines.

The anti-misting component (i.e., the branched polysiloxane component)is included in the composition of the invention (i.e., the coatingformulation) in an anti-misting amount. An anti-misting amount (mistsuppressant amount), is an amount which causes a reduction in misting oraerosoling when the composition of the invention is used in a processwhich ordinarily causes misting or aerosoling of the composition.Typically, the anti-misting component is included in the coatingformulation in an amount of about 0.1 to about 15 weight percent, andmore typically, about 0.5 to about 5 weight percent of the coatingformulation.

The antimisting component results from copolymerizing, underhydrosilylation reaction conditions, one or more organosilicon compoundscontaining at least two unsaturated hydrocarbon functional groups permolecule, i.e., component (a), with one or more silylhydride-containingcompounds containing at least two silylhydride functional groups permolecule, i.e., component (b).

The organosilicon compound of component (a) includes any low molecularweight compound, as well as higher molecular weight oligomers andpolymers, containing one or more silicon atoms and having at least twounsaturated hydrocarbon functional groups. Some examples of classes oforganosilicon compounds of component (a) include organosilanes (i.e.,containing silicon-carbon bonds in the absence of silicon-oxy bonds),siloxanes, and silazanes containing at least two unsaturated hydrocarbongroups.

The unsaturated hydrocarbon groups in the organosilicon compounds ofcomponent (a) include any straight-chained, branched, or cyclichydrocarbon groups having at least one carbon-carbon double or triplebond capable of reacting with a silylhydride group under hydrosilylationconditions. More typically, the unsaturated hydrocarbon group containstwo to six carbon atoms. Some examples of unsaturated hydrocarbon groupsinclude substituted and unsubstituted vinyl, allyl, butenyl, butadienyl,4-pentenyl, 2,4-pentadienyl, 5-hexenyl, cyclobutenyl, cyclohexenyl,acryloyl, and methacryloyl.

Some examples of low molecular weight organosilane compounds ofcomponent (a) include divinyldimethylsilane, divinyldichlorosilane,divinylmethylpropylsilane, divinyldipropylsilane,divinyldiisopropylsilane, divinyldiphenylsilane,divinylphenylpropylsilane, trivinylmethylsilane, trivinylethoxysilane,trivinylchlorosilane, trivinylphenylsilane, diallyldimethylsilane,diallyldichlorosilane, allylvinyldimethylsilane, trivinylphenylsilane,1,3-divinyltetramethyldisilylmethane,1,4-divinyltetramethyldisilylethane,1,1-divinyltetramethyldisilylethane,1,1,4-trivinyltrimethyldisilylethane,1,1,1-trivinyltrimethyldisilylethane,1,1,4,4-tetravinyldimethyldisilylethane,1,1,1,4-tetravinyldimethyldisilylethane,1,1,1,4,4,4-hexavinyldisilylethane,1,3-divinyltetraphenyldisilylmethane,1,4-divinyltetraphenyldisilylethane,1,1-divinyltetraphenyldisilylethane,1,1,4-trivinyltriphenyldisilylethane,1,1,1-trivinyltriphenyldisilylethane,1,1,4,4-tetravinyldiphenyldisilylethane, and1,1,1,4-tetravinyldiphenyldisilylethane.

Some examples of low molecular weight siloxane compounds of component(a) include divinyldimethoxysilane, divinyldiethoxysilane,trivinylethoxysilane, diallyldiethoxysilane, triallylethoxysilane,vinyldimethylsiloxyvinyldimethylcarbinol(CH₂═CH₂—C(CH₃)₂—O—Si(CH₃)₂(CH₂═CH₂), 1,3-divinyltetramethyldisiloxane,1,3-divinyltetraethyldisiloxane, 1,1-divinyltetramethyldisiloxane,1,1,3-trivinyltrimethyldisiloxane, 1,1,1-trivinyltrimethyldisiloxane,1,1,3,3-tetravinyldimethyldisiloxane,1,1,1,3-tetravinyldimethyldisiloxane, 1,3-divinyltetraphenyldisiloxane,1,1-divinyltetraphenyldisiloxane, 1,1,3-trivinyltriphenyldisiloxane,1,1,1-trivinyltriphenyldisiloxane, 1,1,3,3-tetravinyldiphenyldisiloxane,1,1,1,3-tetravinyldiphenyldisiloxane, hexavinyldisiloxane,tris(vinyldimethylsiloxy)methylsilane,tris(vinyldimethylsiloxy)methoxysilane,tris(vinyldimethylsiloxy)phenylsilane, andtetrakis(vinyldimethylsiloxy)silane.

Some examples of linear siloxane oligomers of component (a) include1,5-divinylhexamethyltrisiloxane, 1,3-divinylhexamethyltrisiloxane,1,1-divinylhexamethyltrisiloxane, 3,3-divinylhexamethyltrisiloxane,1,5-divinylhexaphenyltrisiloxane, 1,3-divinylhexaphenyltrisiloxane,1,1-divinylhexaphenyltrisiloxane, 3,3-divinylhexaphenyltrisiloxane,1,1,1-trivinylpentamethyltrisiloxane,1,3,5-trivinylpentamethyltrisiloxane,1,1,1-trivinylpentaphenyltrisiloxane,1,3,5-trivinylpentaphenyltrisiloxane,1,1,3,3-tetravinyltetramethyltrisiloxane,1,1,5,5-tetravinyltetramethyltrisiloxane,1,1,3,3-tetravinyltetraphenyltrisiloxane,1,1,5,5-tetravinyltetraphenyltrisiloxane,1,1,1,3,3-pentavinyltrimethyltrisiloxane,1,1,3,5,5-pentavinyltrimethyltrisiloxane,1,1,3,3,5,5-hexavinyldimethyltrisiloxane,1,1,1,5,5,5-hexavinyldimethyltrisiloxane,1,1,1,5,5,5-hexavinyldiphenyltrisiloxane,1,1,1,5,5,5-hexavinyldimethoxytrisiloxane,1,7-divinyloctamethyltetrasiloxane,1,3,5,7-tetravinylhexamethyltetrasiloxane, and1,1,7,7-tetravinylhexamethyltetrasiloxane.

Some examples of cyclic siloxane oligomers of component (a) include1,3-divinyltetramethylcyclotrisiloxane,1,3,5-trivinyltrimethylcyclotrisiloxane,1,3-divinyltetraphenylcyclotrisiloxane,1,3,5-trivinyltriphenylcyclotrisiloxane,1,3-divinylhexamethylcyclotetrasiloxane,1,3,5-trivinylpentamethylcyclotetrasiloxane, and1,3,5,7-tetravinyltetramethylcyclotetrasiloxane.

Some examples of silazanes of component (a) include1,3-divinyltetramethyldisilazane,1,3-divinyl-1,3-diphenyl-1,3-dimethyldisilazane,1,3,5-trivinyltrimethylcyclotrisilazane,1,3,5-trivinyltriphenylcyclotrisilazane,1,3,5-trivinylpentamethylcyclotetrasilazane, and1,3,5,7-tetravinyltetramethylcyclotetrasilazane.

The polymeric siloxanes (polysiloxanes) of component (a) include any ofthe linear, branched, and/or crosslinked polymers having any two or moreof a combination of M, D, T, and Q groups, wherein, as known in the art,an M group represents a monofunctional group of formula R₃SiO_(1/2), a Dgroup represents a bifunctional group of formula R₂SiO_(2/2), a T grouprepresents a trifunctional group of formula RSiO_(3/2), and a Q grouprepresents a tetrafunctional group of formula SiO_(4/2), and wherein atleast two of the R groups are unsaturated hydrocarbon groups and theremainder of the R groups can be any suitable groups includinghydrocarbon (e.g., C₁-C₆), halogen, alkoxy, and/or amino groups.

Some examples of classes of polysiloxanes suitable for component (a)include the MDM, TD, MT, MDT, MDTQ, MQ, MDQ, and MTQ classes ofpolysiloxanes, and combinations thereof, having at least two unsaturatedhydrocarbon groups.

In a particular embodiment, component (a) is an MD-type of polysiloxanehaving one or more M and/or M^(vi) groups in combination with one ormore D and/or D^(vi) groups, wherein M represents Si(CH₃)₃O—, M^(vi)represents (CH₂═CH₂)Si(CH₃)₂O—, D represents —Si(CH₃)₂O—, and D^(vi)represents —Si(CH₂═CH₂)(CH₃)O—, “vi” is an abbreviation for “vinyl,” andwherein the MD-type of polysiloxane contains at least two vinyl groups.

Some examples of suitable MD-type polysiloxanes for component (a)include the M^(vi)D_(n)M^(vi), M^(vi)D^(vi) _(n)M, M^(vi)D^(vi)_(n)D_(m)M, M^(vi)D^(vi) _(n)M^(vi), M^(vi)D^(vi) _(n)D_(m)M^(vi),MD^(vi) _(n)M, and MD^(vi) _(n)D_(m)M classes of MD-type polysiloxanes,wherein m and n each represent at least 1. Any one or combination of theforegoing types of MD polysiloxanes can be used for component (a). Invarious embodiments, m and n can independently represent, for example, anumber within the ranges 1-10, 11-20, 50-100, 101-200, 201-500,501-1500, and higher numbers.

The D^(vi) groups can also be randomly incorporated (i.e., not as ablock) amongst D groups. For example, M^(vi)D^(vi) _(n)D_(m)M canrepresent a polymer wherein n represents 5-20 and m represents 50-1500,and wherein the 5-20 D^(vi) groups are randomly incorporated amongst the50-1500 D groups.

In other embodiments, the M^(vi) and D^(vi) groups can eachindependently include a higher number of unsaturated functional groups,such as, for example, (CH₂═CH₂)₂(CH₃)SiO— and (CH₂═CH₂)₃SiO— groups forM^(vi) or —Si(CH₂═CH₂)₂O— for D^(vi).

The one or more silylhydride-containing compounds of component (b)includes any low molecular weight compound, oligomer, or polymercontaining at least two silylhydride functional groups per molecule.Some examples of classes of silylhydride-containing compounds ofcomponent (b) include organosilanes, siloxanes, and silazanes containingat least two silyhydride functional groups.

Some examples of low molecular weight compounds of component (b) includedimethylsilane, diethylsilane, di-(n-propyl)silane, diisopropylsilane,diphenylsilane, methylchlorosilane, dichlorosilane, 1,3-disilapropane,1,3-disilabutane, 1,4-disilabutane, 1,3-disilapentane,1,4-disilapentane, 1,5-disilapentane, 1,6-disilahexane,bis-1,2-(dimethylsilyl)ethane, bis-1,3-(dimethylsilyl)propane,1,2,3-trisilylpropane, 1,4-disilylbenzene, 1,2-dimethyldisilane,1,1,2,2-tetramethyldisilane, 1,2-diphenyldisilane,1,1,2,2-tetraphenyldisilane, 1,1,3,3-tetramethyldisiloxane,1,1,3,3-tetraphenyldisiloxane, 1,1,3,3,5,5-hexamethyltrisiloxane,1,1,1,5,5,5-hexamethyltrisiloxane, 1,3,5-trimethylcyclotrisiloxane,1,3,5,7-tetramethylcyclotetrasiloxane, and1,3,5,7-tetraphenylcyclotetrasiloxane.

Some examples of silylhydride-containing silazanes of component (b)include 1,1,3,3-tetramethyldisilazane,1,3,5-triethyl-2,4,6-trimethylcyclotrisilazane,1,2,3,4,5,6-hexamethylcyclotrisilazane, and1,2,3,4,5,6,7,8-octamethylcyclotetrasilazane.

Some examples of silylhydride-containing oligomers and polymers ofcomponent (b) include any of the linear, branched, and/or crosslinkedpolymers having any two or more of a combination of M, D, T, and Qgroups, as described above, and having at least two silylhydridefunctional groups in the oligomer or polymer.

In a particular embodiment, component (b) is an MD-type of polysiloxanehaving one or more M and/or M^(H) groups in combination with one or moreD and/or D^(H) groups, wherein M represents Si(CH₃)₃O—, M^(H) representsHSi(CH₃)₂O—, D represents —Si(CH₃)₂O—, and D^(H) represents—Si(H)(CH₃)O—, and wherein the MD-type of polysiloxane contains at leasttwo silylhydride groups.

Some examples of suitable MD-type polysiloxanes for component (b)include the M^(H)D_(n)M^(H), M^(H)D^(H) _(n)M, M^(H)D^(H) _(n)D_(m)M,M^(H)D^(H) _(n)M^(H), M^(H)D^(H) _(n)D_(m)M^(H), MD^(H) _(n)M, andMD^(H) _(n)D_(m)M classes of MD-type polysiloxanes, and combinationsthereof, wherein m and n each represent at least 1 and can have any ofthe numerical values as described above.

The D^(H) groups can also be randomly incorporated (i.e., not as ablock) amongst D groups. For example, M^(H)D^(H) _(n)D_(m)M canrepresent a polymer wherein n represents 5-20 and m represents 50-1500,and wherein the 5-20 D^(H) groups are randomly incorporated amongst the50-1500 D groups.

In other embodiments, M^(H) and D^(H) groups can independently have ahigher number of silylhydride functional groups, such as, for example,H₂Si(CH₃)O— and H₃SiO— groups for M^(H) or —Si(H)₂O— for D^(H).

According to the invention, at least one component (a) or (b) containsat least three functional groups per molecule. For example, one ofcomponent (a) or (b) can have three functional groups per molecule whilethe other component (a) or (b) contains two functional groups permolecule; or both component (a) and (b) can each contain threefunctional groups per molecule; or one of component (a) or (b) can havethree functional groups per molecule while the other component (a) or(b) contains four functional groups per molecule; or both component (a)and (b) can each contain four functional groups per molecule; and so on.

In one embodiment, components (a) and (b) contain an equal number offunctional groups and are in any molar ratio with respect to each other,including equal or similar molar amounts. In another embodiment, one ofcomponent (a) or (b) contains a higher number of functional groups thanthe other component (a) or (b) and both components are in equal molaramounts.

In another embodiment, the branched polysiloxane follows a branchingpattern similar to a star polymer wherein molecules of either component(a) or (b) having a higher number of functional groups (i.e.,crosslinkers) are in a lower molar amount than molecules of eithercomponent (a) or (b) having a lower number of functional groups (i.e.,extenders). The above-described star polymer pattern is distinct from adendritic pattern in which branching predominates.

For example, one component (a) or (b) can have at least four, five, six,seven, eight, nine, ten, or a higher number of functional groups and bein a lower molar amount than another component (a) or (b) containing twoor three functional groups per molecule.

The unsaturated hydrocarbon functional groups of component (a) can be inany suitable molar ratio to silylhydride functional groups of component(b), e.g., 100:1, 50:1, 25:1, 20:1, 10:1, 1:10, 1:20, 1:25, 1:50, 1:100,and any range of ratios therebetween.

In a particular embodiment, the unsaturated hydrocarbon functionalgroups of component (a) are in a molar ratio to silylhydride functionalgroups of component (b) within a range according to the formula (6−s): 1or 1:(1+t) wherein s represents a number equal to or greater than 0 andless than 5, and t represents a number greater than 0 and equal to orless than 5. Some examples of such molar ratios of functional groups of(a) to functional groups of (b) include 6:1, 5.5:1, 5:1, 4.5:1, 4:1,3.5:1, 3:1, 2.5:1, 2:1, 1.5:1, 1.4:1, 1.2:1, 1:1.2, 1:1.4, 1:1.5, 1:2,1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, and 1:6, and any range ofratios therebetween.

For example, in one embodiment, the unsaturated hydrocarbon functionalgroups of component (a) are in a molar ratio to silylhydride functionalgroups of component (b) within a range according to the formula (4.6−s):1 or 1 (1+s) wherein s represents a number greater than 0 and less than3.6. In another embodiment, the unsaturated hydrocarbon functionalgroups of component (a) are in a molar ratio to silylhydride functionalgroups of component (b) within a range according to the formula(4.25−s): 1 or 1:(1+t) wherein s represents a number equal to or greaterthan 0 and less than 3.25, and t represents a number greater than 0 andequal to or less than 3.25. In yet another embodiment, the unsaturatedhydrocarbon functional groups of component (a) are in a molar ratio tosilylhydride functional groups of component (b) within a range of about4.5:1 to about 2:1.

The viscosity of the branched polysiloxane is typically greater than1,500 centipoise (cPs), where 1 cPs=1 millipascal-second (mPa·s). Moretypically, the viscosity of the branched polysiloxane is about orgreater than 3,000 cPs, and even more typically about 5,000 cPs. Inother embodiments, the viscosity of the branched polysiloxane can beabout or greater than 10,000 cPs, 25,000 cPs, 50,000 cPs, or a higherviscosity.

In one embodiment, tetravalent SiO_(4/2) groups (i.e., Q groups) areexcluded from the branched polysiloxane composition.

In another embodiment, unsaturated hydrocarbon compounds, such as, e.g.,alpha-olefins, are excluded from the component mixture from which thebranched polysiloxane is derived. Some examples of such unsaturatedhydrocarbon compounds include alpha-olefins of the formula CH₂═CHR¹wherein R¹ is selected from halogen, hydrogen, or aheteroatom-substituted or unsubstituted hydrocarbon group having one tosixty carbon atoms. Some heteroatoms include oxygen (O) and nitrogen (N)atoms.

In yet another embodiment, oxy-substituted hydrocarbon compounds, suchas oxyalkylene-containing and/or ester-containing saturated orunsaturated compounds, are excluded from the branched polysiloxanecomposition.

The branched polysiloxane of the antimisting component results from thecopolymerization of component (a) and component (b) underhydrosilylation conditions. By “hydrosilylation conditions” is meant theconditions known in the art for hydrosilylation crosslinking betweencompounds containing unsaturated groups and compounds containingsilylhydride groups.

As known in the art, a hydrosilylation catalyst is required to promoteor effect the hydrosilylation reaction between components (a) and (b)either during or after mixing of the components at a suitabletemperature. The hydrosilylation catalyst typically contains one or moreplatinum-group metals or metal complexes. For example, thehydrosilylation catalyst can be a metallic or complexed form ofruthenium, rhodium, palladium, osmium, iridium, or platinum. Moretypically, the hydrosilylation catalyst is platinum-based. Theplatinum-based catalyst can be, for example, platinum metal, platinummetal deposited on a carrier (e.g., silica, titania, zirconia, orcarbon), chloroplatinic acid, or a platinum complex wherein platinum iscomplexed to a weakly binding ligand such asdivinyltetramethyldisiloxane. The platinum catalyst can be included in aconcentration range of, for example, 1-100 ppm, but is more typicallyincluded in a concentration of about 5 to 40 ppm.

Auxiliary and other components can be included, as necessary, in thecoating formulation of the invention. Some types of auxiliary componentsinclude catalyst inhibitors (as described above), surfactants, anddiluents. Some examples of diluents include the hydrocarbons (e.g.,pentanes, hexanes, heptanes, octanes), aromatic hydrocarbons (e.g.,benzene, toluene, and the xylenes), ketones (e.g., acetone,methylethylketone), and halogenated hydrocarbons (e.g., trichloroetheneand perchloroethylene).

In another aspect, the invention is directed to a coating processwherein the coating formulation of the invention is applied to asubstrate under conditions wherein misting or aerosoling of the coatingformulation is known to occur. During such mist-producing conditions,the coating formulation of the invention will exhibit reduced misting ascompared to the coating formulation without the anti-misting amount ofbranched polysiloxane.

The coating formulation can be applied, for example, by roll-coating, oralternatively, by spraying from a suitable applicator (e.g., a nozzle),wherein the applicator can be still or moving with respect to thesubstrate. Though misting or aerosoling is often caused predominantly bymovement of the applicator with respect to a substrate, misting oraerosoling can be caused by factors other than movement of theapplicator or substrate. For example, misting can be caused partially orpredominantly by the method of application rather than by any motion ofthe applicator relative to the substrate, e.g., in a stationary or slowspraying process.

The coating process of the invention is particularly suitable forprocesses in which the coating formulation is being applied to asubstrate in motion wherein the motion is the primary cause of themisting or aerosoling. The motion can be any kind of motion capable ofcausing misting or aerosoling, e.g., mist-producing levels oftranslational and/or rotational motion.

The substrate can be any substrate on which a coating of the abovecoating formulation is desired. Some examples of suitable substratesinclude paper, cardboard, wood products, polymer and plastic products,glass products, and metal products.

In another aspect, the invention is directed to a hardened (i.e., cured)coating obtained by hardening or curing the above coating formulationafter its application on a substrate. The coating formulation, onceapplied to a substrate, can be cured by any suitable curing method knownin the art, including, for example, hydrosilylation reactioncrosslinking, peroxide curing, photocuring (e.g., UV curing), andelectron beam curing.

The hardened coating can, if desired, be removed from the substrate insuch cases where the coating, absent the substrate, is itself a usefulproduct, e.g., for use as an appliable film. To aid in the separation ofcoating the hardened film from the substrate, a release additive can beincluded in the coating formulation, or a release film applied betweenthe substrate and coating formulation.

Examples have been set forth below for the purpose of illustration. Thescope of the invention is not to be in any way limited by the examplesset forth herein.

EXAMPLE 1 Synthesis of Anti-Mist Component (Branched Polysiloxane)

In this example, the component referred to as Component A is acommercially available difunctional vinyl-terminated polysiloxane of theformula M^(vi)D₁₁₀M^(vi) having a viscosity of 200-300 cPs. Thecomponent referred to as Component B is a commercially availablehexafunctional silylhydride-containing polysiloxane of the formulaM₅₀₀D^(H) _(6.5)M having a viscosity of 6,000 to 15,000 cPs and hydridecontent of 155 to 180 ppm, where 6.5 represents an average number ofD^(H) groups randomly incorporated amongst D groups. The componentreferred to as Component C is a commercially available catalystformulation containing 10% by weight platinum.

To a 1L reactor equipped with an overhead stirrer, GN2 inlet,thermometer, and oil bath was added 168.7 g (ca. 20.2 mmol) of ComponentA, and ca. 0.05 g of Component C. The mixture was agitated for one hourunder ambient conditions. Next, 54.4 g (ca. 1.4 mmol) of Component B wasseparately cooled to 4° C. and then added to the components above withstirring. The mixture was agitated for 15 minutes under ambientconditions and then slowly heated to 90° C. After 30 minutes, somegelling was observed. To the reaction mixture was added 255.5 g ofComponent A at 90° C. The mixture was stirred for two hours at 90° C.,cooled to room temperature (˜25° C.), and discharged from the kettle.The amount of product was 430.9 g, which corresponds to a 90% yield. Theshear viscosity and shear modulus were measured at 12 Hz to be 2.813Pa·s and 201.2 Pa, respectively.

EXAMPLE 2 Synthesis of a Coating Formulation Containing Anti-MistingComponent

A two-gallon plastic pail was charged with 94 parts (1880 g) of acommercially available M^(Vi)D₁₁₀M^(Vi) solution containing 100 ppm Ptand 0.4% diallylmaleate inhibitor). The anti-mist additive was chargedto the pail in the amount of 6 parts (120 g) and mixed with adrill-mounted agitator. The crosslinker, a commercially availablehydride (MD₃₀D^(H) ₁₅M) was added to the pail in the amount of 5.5 parts(110 g). The mixture was mixed thoroughly with a drill-mounted agitator.

EXAMPLE 3 Synthesis of a Coating Formulation Containing Anti-MistingComponent

A two-gallon plastic pail was charged with 87.8 parts (1656 g) of acommercially available M^(Vi)D₁₀₀D^(Vi) _(2.5)M^(Vi) solution containing100 ppm Pt and 0.4% diallylmaleate inhibitor). The anti-mist additivewas charged to the pail in the amount of 6 parts (113 g) and mixed witha drill-mounted agitator. The crosslinker, a commercially availablehydride (MD₃₀D^(H) ₁₅M) was added to the pail in the amount of 6.0 parts(113 g). The mixture was mixed thoroughly with a drill-mounted agitator.

EXAMPLE 4 Coating Process

A pilot coater was used for all coating and misting studies. The fiveroll coater was operated at 3,000 feet per minute. The substrate was an18-inch wide Otis Mill UV350 paper. The coater was equipped withthree-five foot air floatation gas heated dryers that were set to 550°F. Coatweight was set to ca. 0.8 lb/ream. Mist measurements were takenwith a DUSTTRAK 8520 aerosol monitor manufactured by TSI Incorporated(Shoreview, Minn.) while coating paper substrate at 3,000 feet perminute. The measurements were taken above the innergate and outergaterolls at a height corresponding to the point of contact between theback-up roll and the applicator roll.

Thus, whereas there have been described what are presently believed tobe the preferred embodiments of the present invention, those skilled inthe art will realize that other and further embodiments can be madewithout departing from the spirit of the invention, and it is intendedto include all such further modifications and changes as come within thetrue scope of the claims set forth herein.

1. A composition comprising: (i) a silicone-based coating componentsusceptible to misting under mist-producing conditions; and (ii) ananti-misting amount of a branched polysiloxane component resulting fromcopolymerizing under hydrosilylation conditions a component mixturecomprising: (a) one or more organosilicon compounds containing at leasttwo unsaturated hydrocarbon functional groups per molecule, saidunsaturated hydrocarbon functional groups capable of undergoing ahydrosilylation reaction with a silylhydride-containing compound underhydrosilylation conditions; and (b) one or more silylhydride-containingcompounds containing at least two silylhydride functional groups permolecule; provided that (i) at least one component (a) or (b) containsat least three functional groups per molecule; (ii) when one component(a) or (b) has a higher number of functional groups per molecule thananother component (a) or (b) having a lower number of functional groupsper molecule, then the component (a) or (b) having a higher number offunctional groups per molecule is present in a molar amount equal to orlower than the molar amount of the component (a) or (b) having a lowernumber of functional groups per molecule; and (iii) unsaturatedhydrocarbon compounds are excluded from the component mixture.
 2. Thecomposition of claim 1, wherein the unsaturated hydrocarbon functionalgroups of component (a) are in a molar ratio to silylhydride functionalgroups of component (b) within a range according to a formula (6−s):1 or1:(1+t) where s represents a number equal to or greater than 0 and lessthan 5, and t represents a number greater than 0 and equal to or lessthan
 5. 3. The composition of claim 1, wherein the unsaturatedhydrocarbon functional groups of component (a) are in a molar ratio tosilylhydride functional groups of component (b) within a range accordingto a formula (4.6−s):1 or 1:(1+s) where s represents a number greaterthan 0 and less than 3.6.
 4. The composition of claim 1, wherein theunsaturated hydrocarbon functional groups of component (a) are in amolar ratio to silylhydride functional groups of component (b) within arange according to a formula (4.25−s):1 or 1:(1+t) where s represents anumber equal to or greater than 0 and less than 3.25, and t represents anumber greater than 0 and equal to or less than 3.25.
 5. The compositionof claim 1, wherein the unsaturated hydrocarbon functional groups ofcomponent (a) are in a molar ratio to silylhydride functional groups ofcomponent (b) within a range according to a formula (4.6−s):1 where srepresents a number greater than 0 and less than 3.6.
 6. The compositionof claim 1, wherein the unsaturated hydrocarbon functional groups ofcomponent (a) are in a molar ratio to silylhydride functional groups ofcomponent (b) within a range of about 4.5:1 to about 2:1.
 7. Thecomposition of claim 1, wherein one component (a) or (b) has at leastfour functional groups per molecule and is in a lower molar amount thanthe other component (a) or (b) having two or three functional groups permolecule.
 8. The composition of claim 1, wherein one component (a) or(b) has at least six functional groups per molecule and is in a lowermolar amount than the other component (a) or (b) having two or threefunctional groups per molecule.
 9. A composition comprising: (i) asilicone-based coating component susceptible to misting undermist-producing conditions; and (ii) an anti-misting amount of a branchedpolysiloxane component resulting from copolymerizing underhydrosilylation conditions a component mixture comprising: (a) one ormore organosilicon compounds containing at least two unsaturatedhydrocarbon functional groups per molecule, said unsaturated hydrocarbonfunctional groups capable of undergoing a hydrosilylation reaction witha silylhydride-containing compound under hydrosilylation conditions; and(b) one or more silylhydride-containing compounds containing at leasttwo silylhydride functional groups per molecule; provided that (i) atleast one component (a) or (b) contains at least three functional groupsper molecule; (ii) one component (a) or (b) has a higher number offunctional groups per molecule and is in a lower molar amount thananother component (a) or (b) having a lower number of functional groupsper molecule; and (iii) unsaturated hydrocarbon compounds are excludedfrom the component mixture.
 10. A composition comprising: (i) asilicone-based coating component susceptible to misting undermist-producing conditions; and (ii) an anti-misting amount of a branchedpolysiloxane component resulting from copolymerizing underhydrosilylation conditions a component mixture comprising: (a) one ormore organosilicon compounds containing at least two unsaturatedhydrocarbon functional groups per molecule, said unsaturated hydrocarbonfunctional groups capable of undergoing a hydrosilylation reaction witha silylhydride-containing compound under hydrosilylation conditions; and(b) one or more silylhydride-containing compounds containing at leasttwo silylhydride functional groups per molecule; provided that (i) atleast one component (a) or (b) contains at least three functional groupsper molecule; (ii) unsaturated hydrocarbon functional groups ofcomponent (a) are in a molar ratio to silylhydride functional groups ofcomponent (b) within a range of about (6−s):1 or about 1:(1+t) where srepresents a number equal to or greater than 0 and less than 5, and trepresents a number greater than 0 and equal to or less than 5; (iii)one component (a) or (b) has a higher number of functional groups permolecule and is in a lower molar amount than another component (a) or(b) having a lower number of functional groups per molecule; (iv)unsaturated hydrocarbon compounds are excluded from the componentmixture.
 11. A composition comprising: (i) a silicone-based coatingcomponent susceptible to misting under mist-producing conditions; and(ii) an anti-misting amount of a branched polysiloxane componentresulting from copolymerizing under hydrosilylation conditions acomponent mixture comprising: (a) one or more organosilicon compoundscontaining at least two unsaturated hydrocarbon functional groups permolecule, said unsaturated hydrocarbon functional groups capable ofundergoing a hydrosilylation reaction with a silylhydride-containingcompound under hydrosilylation conditions; and (b) one or moresilylhydride-containing compounds containing at least two silylhydridefunctional groups per molecule; provided that (i) at least one component(a) or (b) contains at least three functional groups per molecule; (ii)unsaturated hydrocarbon functional groups of component (a) are in amolar ratio to silylhydride functional groups of component (b) within arange according to a formula (4.6−s):1 or 1:(1+s) where s represents anumber greater than 0 and less than 3.6; (iii) one component (a) or (b)has a higher number of functional groups per molecule and is in a lowermolar amount than another component (a) or (b) having a lower number offunctional groups per molecule; (iv) unsaturated hydrocarbon compoundsare excluded from the component mixture.
 12. A composition comprising:(i) a silicone-based coating component susceptible to misting undermist-producing conditions; and (ii) an anti-misting amount of a branchedpolysiloxane component resulting from copolymerizing underhydrosilylation conditions a component mixture comprising: (a) one ormore organosilicon compounds containing unsaturated hydrocarbonfunctional groups, said unsaturated hydrocarbon functional groupscapable of undergoing a hydrosilylation reaction with asilylhydride-containing compound under hydrosilylation conditions; and(b) one or more silylhydride-containing compounds containingsilylhydride functional groups; provided that (i) one component (a) or(b) has at least four functional groups per molecule and is in a lowermolar amount than another component (a) or (b) having two or threefunctional groups per molecule; (ii) unsaturated hydrocarbon functionalgroups of component (a) are in a molar ratio to silylhydride functionalgroups of component (b) within a range of about (6−s):1 or about 1:(1+t)where s represents a number equal to or greater than 0 and less than 5,and t represents a number greater than 0 and equal to or less than 5;and (iii) unsaturated hydrocarbon compounds are excluded from thecomponent mixture.
 13. A composition comprising: (i) a silicone-basedcoating component susceptible to misting under mist-producingconditions; and (ii) an anti-misting amount of a branched polysiloxanecomponent resulting from copolymerizing under hydrosilylation conditionsa component mixture comprising: (a) one or more organosilicon compoundscontaining unsaturated hydrocarbon functional groups, said unsaturatedhydrocarbon functional groups capable of undergoing a hydrosilylationreaction with a silylhydride-containing compound under hydrosilylationconditions; and (b) one or more silylhydride-containing compoundscontaining silylhydride functional groups; provided that (i) onecomponent (a) or (b) has at least six functional groups per molecule andis in a lower molar amount than another component (a) or (b) having twoor three functional groups per molecule; (ii) unsaturated hydrocarbonfunctional groups of component (a) are in a molar ratio to silylhydridefunctional groups of component (b) within a range of about (6−s):1 orabout 1:(1+t) where s represents a number equal to or greater than 0 andless than 5, and t represents a number greater than 0 and equal to orless than 5; and (iii) unsaturated hydrocarbon compounds are excludedfrom the component mixture.
 14. A coating process comprising applying toa substrate under mist-producing conditions the composition of claim 1,the composition exhibiting reduced misting when subjected to saidmist-producing conditions as compared to the same composition lacking ananti-misting amount of branched polysiloxane component.
 15. A coatingprocess comprising applying to a substrate under mist-producingconditions the composition of claim 2, the composition exhibitingreduced misting when subjected to said mist-producing conditions ascompared to the same composition lacking an anti-misting amount ofbranched polysiloxane component.
 16. A coating process comprisingapplying to a substrate under mist-producing conditions the compositionof claim 3, the composition exhibiting reduced misting when subjected tosaid mist-producing conditions as compared to the same compositionlacking an anti-misting amount of branched polysiloxane component.
 17. Acoating process comprising applying to a substrate under mist-producingconditions the composition of claim 4, the composition exhibitingreduced misting when subjected to said mist-producing conditions ascompared to the same composition lacking an anti-misting amount ofbranched polysiloxane component.
 18. A coating process comprisingapplying to a substrate under mist-producing conditions the compositionof claim 5, the composition exhibiting reduced misting when subjected tosaid mist-producing conditions as compared to the same compositionlacking an anti-misting amount of branched polysiloxane component.
 19. Acoating process comprising applying to a substrate under mist-producingconditions the composition of claim 6, the composition exhibitingreduced misting when subjected to said mist-producing conditions ascompared to the same composition lacking an anti-misting amount ofbranched polysiloxane component.
 20. A coating process comprisingapplying to a substrate under mist-producing conditions the compositionof claim 7, the composition exhibiting reduced misting when subjected tosaid mist-producing conditions as compared to the same compositionlacking an anti-misting amount of branched polysiloxane component.
 21. Acoating process comprising applying to a substrate under mist-producingconditions the composition of claim 8, the composition exhibitingreduced misting when subjected to said mist-producing conditions ascompared to the same composition lacking an anti-misting amount ofbranched polysiloxane component.
 22. A coating process comprisingapplying to a substrate under mist-producing conditions the compositionof claim 9, the composition exhibiting reduced misting when subjected tosaid mist-producing conditions as compared to the same compositionlacking an anti-misting amount of branched polysiloxane component.
 23. Acoating process comprising applying to a substrate under mist-producingconditions the composition of claim 10, the composition exhibitingreduced misting when subjected to said mist-producing conditions ascompared to the same composition lacking an anti-misting amount ofbranched polysiloxane component.
 24. A coating process comprisingapplying to a substrate under mist-producing conditions the compositionof claim 11, the composition exhibiting reduced misting when subjectedto said mist-producing conditions as compared to the same compositionlacking an anti-misting amount of branched polysiloxane component.
 25. Acoating process comprising applying to a substrate under mist-producingconditions the composition of claim 12, the composition exhibitingreduced misting when subjected to said mist-producing conditions ascompared to the same composition lacking an anti-misting amount ofbranched polysiloxane component.
 26. A coating process comprisingapplying to a substrate under mist-producing conditions the compositionof claim 13, the composition exhibiting reduced misting when subjectedto said mist-producing conditions as compared to the same compositionlacking an anti-misting amount of branched polysiloxane component.
 27. Ahardened silicone-based coating or film produced by subjecting asubstrate coated with the composition of claim 1 to one or more curingsteps.
 28. A hardened silicone-based coating or film produced bysubjecting a substrate coated with the composition of claim 10 to one ormore curing steps.